Part 109

The =obturator externus= resembles that of the horse.

The =obturator internus= is extensive and strong; its tendon emerges through the obturator foramen.

The =gemellus= is fused in part with the obturator internus.

The =quadriceps femoris= is more clearly divided than in the horse, and its action is transmitted by a single patellar ligament.

The =capsularis= is absent.

MUSCLES OF THE LEG AND FOOT

The =peroneus tertius= resembles that of the ox, but its tendon is not perforated by that of the tibialis anterior, and ends on the inner (second) large metatarsal bone, detaching a strong branch to the first and second tarsal bones.

The =tibialis anterior= arises on the tibial crest. Its tendon passes over the hock along the inner border of the tendon of the peroneus tertius (both being bound down by an annular ligament), and is inserted into the inner (second) metatarsal and first tarsal bones.

FIG. 228.—MUSCLES OF LEG AND FOOT OF PIG, ANTERO-EXTERNAL VIEW.

a, Tibialis anterior; a′, tendon of preceding; b, peroneus tertius; b′, tendon of b; c, anterior or long digital extensor; d, e, f, f′, f″, tendons of c; g, peroneus longus; g′, tendon of g; h, extensor digiti quarti; h′, tendon of h, which receives h″, from the interosseus medius; i, extensor digiti quinti; k, deep digital flexor; l, soleus; m, gastrocnemius; n, extensor brevis. (After Ellenberger, in Leisering’s Atlas.) ]

The =peroneus longus= lies partly on the outer surface of the peroneus tertius. Its tendon crosses those of the lateral extensor, passes along a groove on the plantar surface of the fourth tarsal bone, and ends on the first tarsal and second metatarsal bones.

The =anterior= or =long digital extensor= arises with the peroneus tertius and is largely covered by it and the peroneus longus. It divides into three parts. The tendon of the =inner division= (M. extensor digiti tertii) ends on the =inner chief= (third) =digit=; that of the =middle division= by two branches on the =principal digits=; and that of the =outer division= by three branches on the =second=, =fourth=, and =fifth digits=.

The =lateral digital extensor= divides into proper extensors of the =fourth= and =fifth digits= (Extensores digiti quarti et quinti).

The =extensor hallucis longus= arises on the fibula and ends on the =inner small= (second) =digit=.

The =extensor digitalis brevis= is well developed and consists of three parts. The inner and outer tendons end on the first phalanges of the chief digits, the middle one joins the common extensor tendon of the same.

The =gastrocnemius= presents nothing special.

The =soleus= is wide, and is partly blended with the external head of the gastrocnemius.

The =superficial digital flexor= has a large belly. Its tendon ends on the two chief digits, and is also connected with the ligaments of the accessory digits.

The =inner head= of the =deep digital flexor= (flexor digitalis longus) is relatively small. The common tendon ends as in the thoracic limb.

The =popliteus= presents no special features.

The =plantar muscles= resemble their homologues of the fore limb, except that the adductors of the accessory digits and the lumbricales are absent.

THE MUSCLES OF THE DOG

MUSCLES OF THE FACE

The =panniculus carnosus= is well developed and presents two distinct bands, one of which is inserted into the lower lip, the other into the scutiform cartilage of the ear.

The =orbicularis oris= is poorly developed. In the upper lip it is divided centrally, and in the lower it is distinct only near the angles of the mouth.

The =levator nasolabialis= is wide and undivided, and ends in the upper lip.

The =levator labii superioris proprius= arises behind the infraorbital foramen, runs forward under the preceding muscle, and ends in numerous small tendons around the nostril, some blending with those of the opposite side.

The =zygomaticus=, long and narrow, arises on the scutiform cartilage, and ends at the angle of the mouth.